Various instruments for performing surgical cutting operations in body lumens, for example, blood vessels, are known in the art.
For example, U.S. Pat. No. 4,909,781 discloses a flexible catheter for opening obstructions in a blood vessel including an annular, rotatable cutter having a flexible coil spring body positioned at one end of a thin, flexible, cylindrical tube adapted for insertion in the vessel.
U.S. Pat. No. 5,030,201 discloses an expandable atherectomy catheter device having an expandable cutting head consisting of deformable cutting members to remove an atheroma or blood clot from a blood vessel.
U.S. Pat. No. 5,071,424 discloses a catheter atherotome comprising a plurality of elongate cutting blades disposed within a catheter for removing plaque from the interior wall of an artery.
U.S. Pat. No. 5,074,871 discloses another form of catheter atherotome having an expansable cutter head at the distal end of a catheter.
All of the above instruments utilize mechanical cutters to remove obstructions in blood vessels.
It is also known to remove obstructions by electrosurgery, i.e., by the use of an electrode, which may or may not be in the form of a sharp blade, which conducts RF electrical energy.
Thus, U.S. Pat. No. 5,057,107 discloses a RF ablation catheter for removing athero-stenotic lesions in blood vessels including a pair of electrodes which create an electric arc for effecting cutting upon application of RF voltage.
U.S. Pat. No. 5,080,660 discloses an electrosurgical electrode having a conductor from which a RF electrical signal is generated, which conductor is surrounded by a sheath having a longitudinal slit to expose the conductor over the region where a surgical procedure is desired.
U.S. Pat. No. 5,163,938 discloses a high-frequency electrosurgical treating device comprising a wire for high-frequency incision in combination with an endoscope. The device is typically used for papillo-sphincterotomy.
The present invention is predicated upon the concept of using an electrosurgical device to perform an incision procedure on the prostate.
Transurethral incision of the prostate (TUIP) is a less traumatic procedure than transurethral resection of the prostate (TURP), the most common operation for benign prostate hyperplasia (BPH). For selected patients TUIP has been found by some urologists to be as effective as TURP, with the advantage that it permits a shorter hospital stay and is associated with fewer complications and undesirable effects.
TUIP is typically performed with a cold (unpowered) knife. It has now been found that the use of an electroctrosurgical (ES) knife, particularly a monopolar electrosurgical knife, powered by radio-frequency (RF) electrical energy from an electrosurgical unit (ESU) makes a cutting operation easier, more direct, and thus less traumatic, than cutting with an unpowered knife. Moreover, use of a RF powered knife permits the convenient application of coagulating power for hemostasis.
However, conventional ES knives are not well adapted for TUIP. The urethra is an elongated, narrow tube about one centimeter in diameter, and the prostate extends radially outward from the urethra and needs to be incised to a depth of up to four centimeters. Accordingly, the instrument should have a configuration with a low profile for atraumatic passage through the urethra, but be adapted to be redeployed into a configuration appropriate for the TUIP procedure. An instrument which satisfies these requirements and also has other advantages is provided by the present invention.